1. Field of the Present Invention
The present invention relates to a data recording/reproducing apparatus such as a rotary head type digital audio tape recorder (hereinafter referred to as R-DAT) and the like which can perform recording/reproducing of digital data.
2. Description of the Prior Art
Up to now, there has been a magnetic recording/reproducing apparatus such as an R-DAT and the like which can reproduce data which has lost part of its original data through error correction in reproduction, by adding some error correction information (such as a parity check code) to the original data when recording digital data on a magnetic tape. Although such an apparatus can correct completely data which very little is lost, it cannot reproduce the original data when a large part of the data has been lost. When using such a magnetic recording/reproducing apparatus as an auxiliary storage of a computer or the like, it is necessary to check a recording state of data after being recorded in order to detect such a situation as this.
For example, therefore, writing heads and reading heads are separately provided and inspection of recorded data is performed by a method called "read after write", namely, a method of reproducing, with a reading head, data written on a magnetic tape by a writing head immediately after writing the data to compare it with the original data. Reliability of data is improved by writing data again when any write error has been detected in the data through inspection of the recorded data by the above-mentioned comparison method and the like.
Generally, an R-DAT performs an azimuth recording by means of two magnetic heads which have their azimuth angles different from each other. It can, therefore, record data in high density by overlapping contiguous tracks on each other. For this reason, a reading head is positioned so that it can reproduced data from the narrow tracks. When tracing a track immediately after recording data on it by means of such a reading head as this, and since a track for data to be next recorded on it has not been formed yet, the reading head reproduces data from a wide track. Since the level of reproducing signal is too high at this time, tracing position of the reading head needs to be shifted slightly.
Since inspection of recorded data in such an R-DAT as mentioned above is performed by a method of comparing data corrected through error correction information with its original data, it has been impossible to detect quantitatively the recording state of the predetermined unit recording area. When repeating a reproducing operation of a magnetic tape a multiple of times, the recording state of the predetermined unit recording area becomes deteriorated due to rubbing between the magnetic tape and the reading head, and the like. There is a case, therefore, that error correction becomes impossible due to the increase in errors after a plurality of reproducing operations even though error correction immediately after recording can correct every error if the data is written in another unit recording area.